Barrel choke means



Nov. 23, 1943. E. F. WHITE .Y 2,335,138

BARREL GHOKE MEANS v l Filed March 13, 1941 Patented Nov. 23, 1943,-

UNITED STATES PATENT OFFICE d assmss v BARREL cnoxn MEANS l Ezekiel Field White. West Hartford, Conn. Application March 13, 1941, Serial No. 383,077

(Cl. l2- 79) 3 claims.

My present invention pertains to gun choking means for the'muzzle end of shotgun barrels, such for example asdisclosed and claimed in my prior Patents Nos. 1,892,522, dated December 27, 1932, and Re. 20,958, of December 27, 1938, a reissue of original ber 21, 1937. More particularly, this invention Vaims to provide means by which -the operation of such chokes is made more eiective, especially in maintaining ,a more uniform and systematical arrangement of the shot mass on emergence from the barrel and during its ight, with resulting correspondingly improved shot pattern at the target.

In the drawing, representing by way of example one illustrative embodiment of the present invention:

Fig. 1 shows the muzzle end of a gun barrel and associated choke means, the view being partly in side elevation and partly in longitudinal vertical section; and

Fig. 2 is a largely diagrammatic view, in longil tudinal section, illustrating the operation'of my improved choking means.

Referring to the drawing in more detail, the gun barrel 3 is externally threaded at its muzzle end, as at 4, for the reception of a correspondingly internally threaded shell 5 projecting forwardly beyond the end of the barrel. This shell 5 has a plurality of slots 6, generally about six in number, equally distributed circumferentially and leading back from its open front end, en-

No. 2,102,931, dated Decemabling the shell to be adjusted to afford different fore end or mouth. `A may be formed about sizes of openings at its circumferential groove I the shell 5 inwardly of the inner ends of the slots 6, for greater ease in flexing the shell segments 8 dened by the slots and reducing likelihood of breakage of the segments adjacent their bases.

Similarly as in my Patent Re. 20,958, a forward portion of each shell-segment 8 has a reduced thickness, such portion being Yformed with an arcuate tapering incline or shoulderA 9 at its inner end, at approximately mid-length of the segments. At their forward ends 'said segments 8 are externally beveled as at I0. The angle of these beveled ends Ill'relative to the shell axis desirably is somewhat larger than the corresponding angle for the shoulders 9. 'I'he number segment need not be limited to one, essential thatthe shell 5 here illustrated as a detachable element be so constructed. In the example shown in Fig. 1 the shell is releasably outer beveled orvtapered formations or shoulders I4 and I5 cooperable respectively with the segment'inclines or shoulders 9 and I 0. The angles of said beveled formations I4 and I5 are vdesirably somewhat larger-than those of the corresponding external inclines 9 and I0 upon the shell segments 8.

As fully explained in adjusting sleeve l2 is turned on and relative to the barrel-end, shell or extension 5 to position the choke segments 8 at the between a condition of full-open bore and that of full choke. 'I'he condition illustrated in Fig. 1 is that 'of substantially non-choke or full-open bore. The threading II, I3 for the shell 5 and the adjusting sleeve I2 may have any suitable pitch, but conveniently .is such that one completeturn of the sleeve will adjust the choke segments between the two extremes. I'n the ex-` ample illustrated, as in my Patent Re. 20,958,-the

calibre or diameter of the immediately adjoin-f ing portion of the bore of the barrel 3.

By reason of said radial enlargement a transverse circumferential annular shoulder 25 is provided at the inner end of the cylindrical face or wall 25 of the non-slotted inner section of the barrel terminal element 5, the latter, in the exampleillustrated, being the detachable shell member and the shoulder 26 being presented by a'portlon of the outer end face of the barrel 3. The inner end section 5a of the barrel terminal chokeelement 5 is recessed to a larger diameter than that of said bore or cylindrical wall 25 of the main part oi.' said my earlier patents, thel desired degree of choke,

element 5, so providing l transverse rearwardly facing annular wall or shoulder 21 adapted to abut the barrel end wall, in this same or substantially the same transverse plane with the forwardly facing shoulder 2i which in this instance is on the barrel.

However, such forwardly facing shoulder may be otherwise formed and located than on the barrel'or directly at its end. depending on the total length desired for the radially enlarged terminall chamber of the choke device, whether the slotted element is detachable or otherwise.

The diametral difference referred to, and the radial extent of the shoulder such as 2l generally is small in actual dimension, and the drawing may be regarded as somewhat exaggerated for the purposes of description. For example, in a 12 gauge shotgun having astandard bore of .729 in. the choke or expansion-chamber diameter may be from about 0.005 to about 0.025 in. greater, giving it a diameter of approximately .739 in. on the average.

The provision of a terminal cylindricalchamber of a diameter greater than that of the main portion of the gun bore, such as defined in Fig. A by the -inner wall 25 of the shelli, has been found in actual practice to aiford a remarkable and unforeseen eifect upon the shot mass attendant on its emergence at and travel from the mouth of vthe choke, in any ofthe adjusted positions of the latter. As clearly shown in Fig. 1 the transition from the relatively smaller bore of the gun barrel to the larger diameter of the choke chamber is abrupt and immediate, the outwardly directed face of the shoulder 26 being substantially perpendicular to the axis ofthe bore.

The operation in this connection, in so far as I have been able to determine it, 'may be explained at least in part as follows, having reference to the largely diagrammatic Fig. 2.

The usual loaded shell or fixed ammunition for Shotguns employs some form of wad or wadding mass behind the mass of shot, separating the latter from the explosive. As represented in Fig. 2 the load of shot and its following wad W have just enteredthe enlargement of the choke chamber 25, immediately in advance of the circumferential shoulder 26. Just before the wad and the load of Ashot reach the end of the barrel proper they have a velocity of approximately 1200 ft. per second and there is then a gas pressure on the Wad perhaps as high as 2000 lbs. per

sq. in. As the wad emerges from the relatively. smaller bore of the barrel proper into the enlarged chamber some of the gases under that 2000 lb. pressure escape by the wad and rush ahead of the shot charge. Consequently there is produced a zone of very high gas pressure ahead of and surrounding the shot charge. This high pressure gas zone is effective on and very probably extends out into the atmosphere ahead of the gun barrel, into which. the shot charge emerges. The high pressure gas of this zone very quickly expands in al1 directions, especially laterally, and in so doing it imparts to the shot a suflcient lateral motion to cause them to distribute with more uniformity than customary, thus improving the pattern.

The quantity of the gases escaping by the wad can be controlled to give the desireddispersion to the shot by varying .the diameter of the described chamber. For a l2 gauge shotgun having a standard bore of .729 in. it has been found that the optimum dispersion is had when the diameter of the chamber is about .739 in. By increasing or decreasing the differential of this chamber diameter with respect to the bore of the barrel, as contemplated by the invention, the desired correspondingly varied dispersion and pattern results may be obtained.

The described dispersion effect of the shot charge resulting from the novel provision for advance escape of gases at and under the cooperative control of the choke is maximum with the choke adjusted to its wide open position. 'I'he choke bore is then substantially straight, that is, a true cylinder, and as herein disclosed is some 0.010 in. larger in diameter than the barrel bore. As the choke device is adjusted to less open positions, herein'by rotating the sleeve I2 to flex the choke segments 8 inwardly, said 0.010 in. differential or excess diameter, at the front of the' choke is neutralized, and in the more closed positions the front diameter of the choke becomes .less than the barrel bore.

Taking again the example of a 12 gauge shotgun, having a standard barrel bore of .729 in., the diameter of the choke bore or chamber at its rear portion (and throughout in its wide open position) is approximately .739 in., and the total adjustment for the front of the choke is about 0.0,36 in. This gives the desired full choke of approximately 0.026 in. below the .729 in. barrel bore, closing the choke front end to the appropriate diameter of substantially .703 in. for the full choke position in a 12 gauge gun.`

The described increased dispersion effect as had with the improved choke structure of the present invention, and which is maximum with the choke wide open, is gradually reducible through the various adjusted positions of increasing choke, until in the full choke position it is largely eliminated. Thus through the total cooperative relation and effect Aof the choke chamber enlargement and the adjustability of the choke, I obtain the highly desirable new result of a greater opening or expansion of the shot pattern, in the full open position of the choke, by reason of the advance gas escape action, yet in the full choke position the dispersion of the shot is held to an entirely acceptable minimum. One practical major result of this novel choke system may be described as the provision of a shotgun variable choking means or device affording at close range a pattern 'which is not only about two stages more open than heretofore obtainable in a wide open gun of the corresponding gauge but is also distinctly improved as to the distribution of the shot in that pattern, said means or device nevertheless, at full choke, giving a pattern of exceptional quality and density, and proportionately so through the various intermediate adjusted choke positions.

My invention is not limited to the particular embodiment thereof illustrated and described4 herein, and I set forth its scope in my following claims. f

I claim:

1. An adjustable choke for a shotgun of given barrel gauge, said choke comprising a tubular cylindrical shell having a rear portion including a terminal attaching section and an imperforate bore section in advance thereof and said shell having an integrally continuous forward portion divided longitudinally into yieldable segments, an imperforate adjusting sleeve on and movable along said shell, the exterior faces of the shell segments and the interior face of said sleeve having shoulders inclined at relatively different angles and interengageable to contract assunse i 3 said segments as between full-open, intermediate and full-choke positions, said terminal attachportioned to aord the choke a full-open position of greater internal diameter for the segmented portion than the given barrel gauge, an intermediate position equivalent in internal diameter to such barrel gauge and a full-choke position of 'n internal diameter less than the barrel gauge, and -in all of which positions there is presented in ad- Vance of the shell attaching section a circumferentially closed annular chamber of internal diameter exceeding the barrel gauge and providing for controlled advance escape of gases.in each position of the choke.

2. In a shotgun, in combination, a barrel having a bore of given gauge, an adjustable choke comprising a cylindrical shell having its forward portion divided longitudinally into yieldable segments, an imperforate sleeve on and adjustably movable lengthwise the shell, the exterior faces of said segments and the interior face of said sleeve having differently inclined interengageable shoulders for contracting said segments from parallel to angular relation to the shell axis, said shell having rearwardly of its segmented portion an imperforate bore section and a terminal attaching section fitted to the barrel muzzle, said bore section and said segmented forward portion in its non-contracted position having internal di- CERTIFICATE Patent No. 2,555,158.

EZEKIEL FIELD WHITE.

ameters exceeding the barrel bore thereby. to present a chamber of abruptly increased cross-sectional diameter at the end of the barrel for the advance escape of gases to modify shot disper- 6 sion and vpattern in all adjustments of the choke,

and said segmented forward shell portion and said adjusting sleeve correlatively with said chamber providing variable adjustment as to internal diameter at the fore end of the choke 10 through a range between a maximum at least substantially equal to that of said chamber and a minimum below that of the barrel above.

3. An adjustable choke for shotgun barrels, said choke comprising a cylindrical shell 'havingan imperforate rear portion of fixed uniform internal diameter and a front portion divided longitudinally into transversely yieldable segments, said segments having spaced inclined shoulders on their outer faces, an imperforate sleeve threaded ony the shell and having at its interior spaced inclined shoulders adapted to engage said segment shoulders for contracting the segments out of parallel relation to the shell axis, said segmented front portion of the shell having fullopen. full-choke and intermediate positions including an intermediate position wherein the internal diameter at the segment fore ends is less than that of the rear portion of the shell but is equivalent to and thereby determines the barrel gauge for which the particular choke is adapted,

said segment fore-end internal diameter in the full-open position being at least as large as that of said rear portion of the choke shell, and said rear portion of the choke shell adapted to pre- 5 sent at the barrel muzze a charge-surrounding annular space for the controlled advance escape of gases at the mouth of the shell and thereby affording improved shot dispersion and pattern results, for all positions of the shell segments.

EZEKIEL FIELD WHITE.

OF CORRECTION.

November 25, 19).;5.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring eorrecti on as follows;

Page 5, second column, line l2, claim 2, for "above" read --bore; line 55, claim 5 and that the said Letters Patent should be 'read with this correction therein that the same may conform to the record of the case in the Patent Office.

signed and Sealed this 18th day of Januar-y, A. D. 19th.

(seal) Henry Van Arsdal, Acting Commissioner of Patents.

v CERTIFICATE OF CORRECTION. Patent No. 2,555,158. November 25, l9ll5.

EZEKIEL FIELD WITTE.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, sec- Orld column, line l2, claim 2, for "above" read -bore; line 55, claim 5, for "muzze read -muzzle; and that the said Letters Patent should be 'read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 18th day of January, A. D. 19ML.

Henry Van Arsdale', (Seal) Acting Commissioner of Patents. 

